Boy I'm posting too much here...

I seem to have solved the problem with the mount by sanding it where it is bolted to the firewall, and then tightening the bolts down hard - I'm getting there.

Another question: did you guys put foam under the tank, as well as around it? The area behind the firewall seems to be designed with space for foam on 3 sides, but not the bottom. If I squish foam under the tank, it will probably end up tilted, which is obviously less than ideal. What did you lot do?

Thanks,
Matthew